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Introduction
The postoperative period, particularly the initial hours following cardiac surgery, is a critical window in patients with CHD. Within this timeframe, they are susceptible to haemodynamic or clinical challenges that may precipitate severe complications, increasing the risk of morbidity and mortality in the paediatric cardiac ICU. Hence, the timely identification and management of potential complications are imperative to ensure a favourable prognosis. Reference Asoh, Hickey and Dorostkar1,Reference Kasar, Cansaran-Tanidir and Ozturk2
According to the American Heart Association, the recommendations for performing cardiac catheterisation in patients during the early postoperative period are as follows: Reference Nicholson, Kim, Vincent, Kogon, Miller and Petit3,Reference Feltes, Bacha and Cheatham8,11
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1. Patients who require mechanical cardiopulmonary support without a clear cause.
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2. When there is a high suspicion of residual structural lesions and non-invasive diagnostic tools have not identified the cause of clinical and/or haemodynamic compromise.
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3. It would be reasonable to perform cardiac catheterisation in patients who do not exhibit the expected clinical outcome, including:
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– Severe or persistent cyanosis.
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– Low cardiac output.
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– Failure to wean from inotropic or ventilatory support.
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– Echocardiographic diagnosis of residual defects with significant haemodynamic impact.
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– Persistent ascites or pleural effusions.
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4. Patients with univentricular physiology who have undergone total cavopulmonary connection and:
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– Exhibit signs of low cardiac output secondary to elevated pulmonary vascular resistance with minimal or no response to medical treatment, in order to perform fenestration of the extracardiac tube to the atrial cavity or to open up the fenestration.
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– Display chronic and progressive deterioration, with the objective of assessing haemodynamic status, pressure, and pulmonary vascular resistance in all segments, telediastolic function of the systemic ventricle, anastomosis, fenestration, and gradients, in order to determine whether the case requires exclusive medical management, intervention, or reoperation, including possible takedown of the total or bidirectional cavopulmonary connection.
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In ICUs of developing countries with limited experience in interventional procedures, these procedures during the immediate postoperative period are generally discouraged due to these patient’s critical condition. Additional considerations include recent suture lines, the challenges of transporting patients to the cath lab, and the potential risk of kidney injury from contrast use. However, research indicates that cardiac catheterisation, including interventional procedures, can be safely conducted during the first hours of the postoperative period when overseen by a multidisciplinary team with broad experience and expertise.
Research has suggested there is a correlation between the waiting period for the initial surgical event and the timing of post-surgical catheterisation may contribute to elevated rates of morbidity and mortality. Asoh’s 2009 study underscored that delayed imaging, specifically diagnostic catheterisation more than two weeks after surgery and warranting subsequent surgical intervention, was associated with diminished survival rates. Consequently, any delay in performing a postoperative catheterisation leads to a delay in diagnosis and the timely implementation of appropriate therapeutic measures. Reference Asoh, Hickey and Dorostkar1,Reference Odegard, Bergersen and Thiagarajan4,Reference Zahn, Dobrolet, Nykanen, Ojito, Hannan and Burke5
This article aims to demonstrate the safety and benefits of cardiac catheterisation within the initial 72 hours following cardiovascular surgery to manage CHD.
Material and methods
This retrospective case-control study was conducted in paediatric patients, ranging in age from newborns to under 18 years, who underwent cardiac surgery and required cardiac catheterisation within the initial 72 hours post-surgery at a national referral hospital in Mexico City between January 2003 and December 2022. The research team identifies the initial 72-hour postoperative period as a critical phase in patient recovery; therefore, we defined this timeframe as the focus of our investigation. The patients were stratified according to the type of indication for catheterisation admission, either diagnostic (control) or interventional (case). A diagnostic indication was defined as the absence of the residual lesion detected in previous non-invasive studies (echocardiography or computed tomography), but the patient´s postoperative course was not optimal. Interventional indication was defined as any residual lesion identified through non-invasive imaging modalities that necessitated a haemodynamic intervention.
The subgroup that underwent interventional catheterisation was further analysed and categorised based on interventions performed in a recent suture site. Patients who received interventions at the suture site did not undergo procedures in any other location. Institutional approval was obtained from local investigation and ethics committees.
Data collection and definitions
Clinical data were collected from electronic and physical medical records. The included variables were: sociodemographic characteristics (age, weight, gender), surgical factors (prior surgeries, cardiopulmonary bypass, surgical complications, type of surgery), catheterisation details (diagnostic or interventional, complications, type of intervention, timing of the post-surgical catheterisation, the need for subsequent catheterisation, the time to death post-catheterisation), and outcomes of interest (catheterisation-related complications, complexity of the CHD, complexity of the surgical technique, and mortality).
Statistical analysis
Continuous variables are summarised as medians and interquartile ranges, and their distribution was assessed with the Shapiro test. Categorical variables are presented as absolute frequencies and percentages. The Chi-square test and Fisher’s exact test were used to compare categorical variables and Wilcoxon’s test for continuous variables. Univariate and multivariate logistic regression models were constructed to assess the association between variables of interest and mortality, and the estimates were reported as odds ratios and 95% confidence intervals (95% CI).
All tests were two-tailed, and a p-value <0.05 was considered statistically significant. Statistical analyses were performed with R version 4.3.2.
Results
The study included a total of 6,243 surgeries, of which 264 were catheterisations conducted within the first 72 postoperative hours. The predominant age group encompassed preschoolers (between 1 and 4 years) (35.9%, n = 109), with a female majority (53.8%, n = 142), and the group´s median weight was 14 kg (interquartile range: 2.3–64 kg). The most prevalent diagnoses were tricuspid atresia (17%, n = 46), double outlet right ventricle (12%, n = 32), tetralogy of Fallot (11%, n = 29), and pulmonary atresia without ventricular septal defect (11%, n = 29).
Background
Thirty-nine-point eight per cent of patients (39.8%) (n = 108) had a history of previous surgical intervention, and the most frequent were systemic-to-pulmonary shunts (54%, n = 57), the bidirectional Glenn procedure (24%, n = 10), and pulmonary artery banding (13%, n = 14). Additionally, 23.9% (n = 63) had undergone pre-surgical interventional catheterisations, and the most frequent causes were stent placement in the ductus arteriosus (38%, n = 24), atrial septostomy (20.6%, n = 13), and stent placement in systemic-to-pulmonary shunts (15.8%, n = 10).
Current surgery
In the total group, 73.5% (n = 194) underwent a single surgical procedure (total cavopulmonary derivation, Jatene procedure, tetralogy of Fallot correction, among others). Two or more surgical interventions during the same event were required in 26.5% of patients (i.e., aortic commissurotomy and enlargement of the pulmonary valve annulus with a bovine pericardial patch). More than one surgical intervention was defined as the need for two procedures following two different surgical techniques.
Cardiopulmonary bypass was warranted in 60% (n = 159) of surgeries. Complications developed in 23.1% (n = 61) of cases, whereby bleeding (39.7%, n = 27), low cardiac output syndrome (14.7%, n = 10), and injury to the pulmonary artery branch or pulmonary artery trunk (10.2%, n = 7) were the most frequent.
Postoperative catheterisation
The primary indications for catheterisation were low cardiac output (29.9%, n = 79), suspected major residual lesions (17.8%, n = 47), and suspected systemic-to-pulmonary shunt obstruction (10.9%, n = 29). In total, 426 residual lesions were successfully addressed via catheterisation procedures.
Seventy-two-point four per cent (72.4%) (n = 192) of patients were admitted to the cath lab for interventional catheterisation due to suspected residual lesions that were previously detected in other non-invasive imaging studies. We also identified another group of patients admitted to the cath lab for diagnostic catheterisation (27.6%, n = 73), who had no evidence of residual lesions but whose unfavourable course required management to prevent clinical progression. In this latter group (diagnostic caths), we identified residual lesions in 44 patients, three of whom warranted device placement via an interventional procedure. For the remaining patients, the complexity of the lesions precluded catheterisation intervention, necessitating a second surgical procedure to address the lesions. The most frequent surgical reinterventions were: right ventricular outflow tract enlargement, pulmonary branch patching, takedown of bidirectional superior cavopulmonary shunt, and placement of systemic-pulmonary fistula.
When comparing patients who underwent interventional catheterisation vs. diagnostic catheterisation, we detected that those patients who required interventional catheterisation had a more frequent history of prior surgery (diagnostic, 27.8% (n = 20) vs. interventional, 44.3% (n = 85), p = 0.015). The frequency of surgical reintervention was greater in patients with a diagnostic indication 56.9% (n = 41) than in patients with an interventional one 22.9% (n = 44), and the difference was statistically significant (p < 0.001). Likewise, patients with delayed sternal closure underwent diagnostic catheterisation more frequently (p = 0.014). The Risk Adjustment for Congenital Heart Surgery-3 score distribution showed significant statistical differences between both groups (58.3% vs. 66.1%, p = 0.017). There was no association between the duration of the intensive care stay and the number of vasoactive drugs used (Table 1).
Characteristics associated with catheterization type
The most frequent procedures performed by interventional catheterisation were pulmonary artery branch angioplasty with stent placement (28.7%, n = 55), stent placement in the fenestration of total cavopulmonary shunt (20.9%, n = 40), atrial septostomy (12.5%, n = 24), and pulmonary-to-systemic shunt angioplasty with stent placement (11.5%, n = 22).
Markedly, among the 192 patients who underwent interventional catheterisation, 70.3% (n = 135) were intervened at the suture site, and there were no statistically significant differences observed in the frequencies of mortality, complications, or the need for surgical reintervention (Table 2).
Characteristic associated with intervention at recent suture sites
However, it is essential to mention that the two complications that arose immediately following catheterisation were all observed in patients who were intervened via the suture sites. These complications included rupture of the suture site in a systemic-to-pulmonary shunt and laceration of the pulmonary artery branch.
Second cardiac catheterisation
Eleven (11) patients required a second cardiac catheterisation, primarily driven by indications such as low cardiac output (27%, n = 3), obstruction of the systemic-to-pulmonary shunt (18%, n = 2), and pulmonary artery stenosis (18%, n = 2). A second catheterisation was done within 48 hours after the initial procedure. Of these, six patients underwent surgical reoperation and five patients received placement of a second device. The most frequently performed procedure was pulmonary artery angioplasty with stent placement (27%, n = 3).
Patients requiring a second surgery
Surgical reoperations were performed on 85 patients in total, comprising 41 patients from the diagnostic catheterisation group, where residual lesions were unsuitable for initial haemodynamic treatment; and 44 patients who received initial interventional management of residual lesions, but failed to show clinical improvement. The second group (initially treated with interventional catheterisation) required reoperation due to residual lesions not resolved or for takedown of current surgery (in cases of univentricular palliative surgery). Within this latter group, the six patients who underwent a second cardiac catheterisation are included.
Patients requiring a third surgery
Among the 85 patients who underwent reoperation, six continued to experience poor clinical results, leading to a third cardiac catheterisation that identified persistent residual lesions necessitating further surgical intervention. Unfortunately, three of these six patients died.
Mortality
The recorded mortality rate stood at 22.3% (n = 59). Of these, 45.8% (n = 27) died within the initial 24 hours post-catheterisation, 16.9% (n = 10) between 25 and 48 hours later, 6.8% (n = 4) between 49 and 72 hours later, and 30.5% (n = 18) 72 hours after catheterisation. Of the total deaths, 49.1% (n = 29) of patients underwent surgical reoperation. Twelve of these patients succumbed within the first 24 hours following catheterisation. Twenty-nine patients (49%) who died had a history of previous surgery or catheterisation.
Children between the ages of 1 and 9 had a lower risk of death (odds ratios 0.14, 95% CI 0.04–0.46 and odds ratios 0.06, 95% CI 0.02–0.23) (Figure 1). There was no significant correlation between the length of stay in the paediatric cardiac ICU and the surgical risk stratification scale, irrespective of whether the catheterisation was interventional or diagnostic (p = 0.7 vs. p = 0.43).
Mortality.
Additionally, we observed no association between the use of vasoactive support and mortality (p = 0.27). However, a strong association was detected between the number of vasoactive drugs administered and mortality, with an increased risk of death among patients administered more than 3 to 4 drugs (p 0.001). Surgical reintervention (odds ratios 3.15, 95% CI 1.56–6.48) was identified as a significant risk factor for mortality.
Seventeen (17) patients (6.4%) were extubated in the initial 24 hours post-catheterisation, 35 patients (13.2%) between 25–48 hours later, and 31 patients (11.7%) between 73–96 hours later. The average duration of stay in the paediatric cardiac ICU was 11 days (range: 1 to 90 days). The Risk Adjustment for Congenital Heart Surgery-1 risk stratification scale, category 3, was the most common in our study population (n = 169).
Discussion
Postoperative care in patients with CHD remains a challenge in the cardiovascular ICU. Anatomical peculiarities, heart function, and residual lesions must be considered in all stages of critical management.
Therefore, an effective tool that provides an appropriate diagnosis and treatment is needed to improve survival and decrease the rate of complications leading to prolonged hospital stays and unfavourable outcome.
Significant myocardial dysfunction can lead to a complicated course in the initial postoperative hours; however, residual lesions must also be considered as causes of poor outcomes. In these cases, catheterisation serves as a crucial diagnostic tool to identify or rule out residual lesions, determine the extent and site of involvement, and guide planning for subsequent surgical or interventional procedures. Reference Kasar, Cansaran and Ozturk7,Reference Feltes, Bacha and Cheatham8
In this study, we identified complex pathologies (tricuspid atresia, double outlet right ventricle, tetralogy of Fallot, among others) that required very specific surgical interventions with a certain level of difficulty. Several of these complex pathologies necessitated surgical or interventional catheterisation approaches prior to the current surgical intervention; contributing to the risk of postoperative complications that required admission to cardiac catheterisation for management of residual lesions.
An example is illustrated by patients with a history of stent placement in the ductus arteriosus or a right ventricular outflow tract to ensure pulmonary flow in that initial stage; once intervened for the actual correction, they showed severe stenosis due to trunk or pulmonary branch deformity upon stent removal. These patients warranted admission to catheterisation for stent placement in the pulmonary branches after surgery.
Patients requiring admission to the cath lab within the first hours postoperatively are those who are severely ill due to suboptimal recovery despite medical intervention. In our study, we did not find a direct association between mortality and cardiac catheterisation. However, we identified that a significant number of patients who died had a history of previous procedures before the current surgery (surgical or haemodynamic) and also required reoperations after the current surgery, demonstrating the complexity of CHD. Therefore, it should be considered that these patients who underwent postoperative catheterisation were in a critical state, and if the procedure had not been performed, the outcome would likely have been unfavourable.
On these bases, it is evident that the complexity of heart disease, the patient´s history, and the development of complications during surgery account for the fact that cardiovascular patients represent a challenging population in developing countries in terms of management in the cardiovascular ICU. This explains why, in the past few years, catheterisation has become most relevant in the identification and resolution of problems in a critical stage. Reference Kasar, Cansaran and Ozturk7,Reference Feltes, Bacha and Cheatham8
Various authors Reference Eraso-Díaz del Castillo, Escobar-Díaz, Lince Varela, Díaz Medina and Cañas Arenas6,Reference Kasar, Cansaran and Ozturk7,Reference Kojima, Imamura and Osada10 recommend waiting for a period of six months between the initial cardiovascular surgery and the catheterisation procedure to allow for the appropriate healing around the anastomotic sites. Our study found no statistically significant differences in mortality risk associated with intervention at recent surgical sites; supporting the alternative of performing haemodynamic procedures within 72 postoperative hours, with minimal risk of severe complications during catheterisation. Furthermore, we identified an improvement in clinical outcomes in various patient groups, such as those who were successfully extubated and progressed within 98 hours following catheterisation. Notably, the population with the highest mortality rate consisted of patients requiring surgical reinterventions or those with a history of previous procedures prior to the current surgery.
There are currently some reservations about the performance of interventional procedures in the immediate postoperative period since these patients tend to be in a critical state, in association with other factors such as the presence of recent suture sites, the implicit difficulties in their transportation to the cath lab, and the risk of kidney injury due to the contrast medium Reference Feltes, Bacha and Cheatham8,Reference Rosales, Lock, Perry and Geggel9 ; despite these obstacles, immediate catheterisation admission can significantly improve patient outcomes when initial signs of complications or suspected lesions emerge. Most patients in our study underwent interventional procedures at recent surgical sites; the most common indication was low cardiac output state, followed by residual lesions compromising patients' haemodynamic status.
Based on the above, we can highlight that although intervention at the recent suture site remains a major concern, we did not find a statistically significant association with mortality risk. However, it is crucial to note that both catheterisation-related complications occurred at recent suture sites, one of which was resolved and the patient had an adequate recovery. Therefore, the risk of complications in this patient group should not be dismissed, and a properly trained surgical team should be available to urgently address these complications.
Conclusion
Based on the preceding discussion, many factors influence the patient´s course in the first hours after cardiovascular surgery. Among them, we can underscore the complexity of the underlying heart disease, the surgical procedure, the patient´s history (previous surgeries and interventional catheterisations such as stent or other device placement), the development of complications during surgery, and the need for surgical reinterventions due to significant residual lesions. 11,Reference Simpson, Moore and Teitel12
The early identification of structural injuries or functional abnormalities that compromise the patient´s haemodynamic state is of pivotal importance to appropriately manage a patient in a critical state. Cardiac catheterisation is thus an essential tool for the identification and resolution of these problems.
Despite reservations regarding the optimal timing, the benefits of these procedures currently outweigh the risks. Therefore, we recommend cardiac catheterisation as soon as residual lesions are suspected or poor clinical outcomes are observed in the early hours following cardiac surgery.
Limitations
This study was conducted at a single centre retrospectively, which inherently includes biases associated with record review.
Being retrospective and descriptive in nature, it is limited in scope. Nonetheless, it provides a foundational basis for potentially altering the approach to analysing cases with similar diagnoses and serves as groundwork for future studies to expand upon.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1047951125000319.
Acknowledgements
The authors express their gratitude to the Departments of Pediatric Cardiology, Cardiovascular Surgery, and the Pediatric Cardiac Intensive Care Unit at the National Institute of Cardiology “Ignacio Chávez” for their invaluable assistance and the information provided for this study.
The authors express their gratitude to the Oficina de Apoyo Sistemático para la Investigación Superior at the Instituto Nacional de Cardiología for their invaluable methodological and statistical assistance in this project.
Financial support
This project received no external funding.
Competing interests
The authors listed above declare no financial or non-financial conflicts of interest related to this topic or manuscript.
Ethical standards
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national guidelines on human experimentation, Reglamento de la Ley General de Salud en Materia de Investigación, and with the Helsinki Declaration of 1975, as revised in 2008. The institutional committees have also approved the study with registration number CI-016-2024.
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